I’m paying €160/month for a workplace (half big room) in the center of Madrid. All included. Is not an office, but a big old flat we (several freelancers, architects, translators…) refurbished for working. Since a couple of years many business related with co-working are merging all around the city, so right now you can find nice and well located places to work for €100-€200.

This is not expensive at all. I share a flat with 3 other students and I pay 220E for the room (fees not included) in Valencia.

Well, mine is just for working, living places are more expensive. 220€ for a flat with 3 others is a resonable price, anyway i think Valencia is mostly the same as Madrid in term of renting prices. Outside the city, for example, in El Escorial, (45km) where i belongs to (a fantastic place, btw), you can get a really nice flat just for you for 500€.